Quinonediimonium salts

ABSTRACT

A DEFINED CLASS OF N,N,N&#39;&#39;,N&#39;&#39;-TETRARRYLQUINONEDIIMONI UM AS SALTS USEFUL INFRARED ABSORBERS IS DISCLOSED; ESPECIALLY THE N,N,N&#39;&#39;,N&#39;&#39;-TETRAKIS(P-DIALKYLAMINOPHENYL)-PBENZOQUINONEDIMONIUM SALT, SUCH AS N,N,N&#39;&#39;-TETRAKIS (P-DIETHYLAMINOPHENYL) - P - BENZOQUINONEBIS(IMONIUMHEXAFLUOROANTIMONATE. THE DIMONIUM SALTS ARE OBTAINED BY OXIDATION OF N,N,N&#39;&#39;,N&#39;&#39;-TETRAARYLARYLENEDIAMINES WITH SILVER SALTS OR BY ELECTROLYTIC METHODS.

United States Patent Office 3,637,769 Patented Jan. 25, 1972 ABSTRACT OFTHE DISCLOSURE A defined class of N,N,N,N,-tetraarylquinonediimoniurnsalts useful as infrared absorbers is disclosed; especially theN,N,N,N-tetrakis(p-dialkylaminophenyl)-pbenzoquinonediimonium salts,such as N,N,N',N'-tetrakis (p-diethylaminophenyl) pbenzoquinonebis(imoniumhexafluoroantimonate). The diimonium salts areobtained by oxidation of N,N,N',N-tetraarylarylenediamines with silversalts or by electrolytic methods.

This application is a continuation-in-part of application, Ser. No.333,729, now abandoned, filed December 26, 1963, which, in turn, is acontinuation-in-part of application, Ser. No. 281,059, filed May 16,1963, now abandoned.

This invention relates to a new class of quinonediimonium salts and tothe use of said salts as infrared absorbers.

The new diimonium salts of the invention are represented by thefollowing formula:

(I) F "I i R B i L Jn l r B3 D t 1 11 R2 wherein A, B, D, E and Rrepresent benzene or naphthalene radicals; n is 1 or 2; R, R R and Rrepresent hydrogen, alkyl, alkoxy, alkenyl, aralkyl, aryl, alkaryl, acylor radicals, said R and R in turn representing hydrogen, alkyl, alkenyl,aralkyl, aryl, alkaryl or acyl radicals; said A, B, D, E and F and Rthrough R which are other than hydrogen being either unsubstituted orsubstituted with inert groups such as lower alkyl, lower alkoxy,hydroxy, cyano, carboxy, sulfo, halogen and the like; and X representsan anion.

The diimonium salts of Formula I are derived from N,N'-substituteddiamino compound of the formula:

II RBN A -N-FRa wherein A, B, D, E and F and R through R have the samemeaning as in Formula I, by the oxidation of two of the amino groupsthereof to form the diimonium cation, as described hereinafter.

The compounds of Formula II may be prepared as follows. On the one hand,a compound having the formula (III) H N{-A3-NH wherein A has the samemeaning as in Formulas I and II is reacted with a substituted orunsubstituted halobenzene or halonaphehtlene, any substituent presenttherein being any one of those within the definition of R, R R or Rgiven above in connection with Formulas I and II, except A typicalreaction is that of a halobenzene and p-phenylenediamine, as follows.

hal HzN NHz \alkali [QJT Q- tQl. (A compound of Formula H) On the otherhand, in instances where R, R ,R and R of Formula II represent OzN- halH N-@-NH;

\alkali (Compounds of Formula II) On Reaction 3, RZ represents analkylating agent in which R corresponds to R or R in Formula II.Suitable RZ compounds are set forth hereinbelow.

Reaction 1 and 1a are carried out in suitable solvent, preferablydimethylformamide, in the presence of an alkali, such as sodium orpotassium carbonate and optionally and preferably in the presence ofcopper powder. The reactions can be effected in a step-Wise fashion, sothat from 1 to 4 of the amino hydrogens (of the diamine) are replaced,thereby permitting preparation of unsymmetrical derivatives.

With respect to Reaction 1, illustrative halobenzenes which may be usedinclude, for example, iodobenzene,

bromobenzene, p-iodotoluene, o-iodotoluene, m-bromotoluene,p-iodododecylbenzene, p-iodoallylbenzene, 4-bromodiphenylmethane,4-bromodiphenyl, 4-iodoacetophenone, 4-bromobenzophenone,3-bromoanisole, etc.

Also, utilizable halonaphthalenes include l-iodonaphthalene,2-bromonaphthalene, 1-bromo-4-methylna hthalene,1-bromo-4-butoxynaphthalene, 1-bromo-4-ethylnaphthalene,1-iodo-6-methoxynaphthalene, etc.

With respect to Reaction 1a, nitro-substituted halobenzones which may beused include mand p-nitrohalobenzenes, such as p-nitrochlorobenzene,m-nitrochlorobenzene, p-nitrobromobenzene, o-nitroiodobenzene,p-nitrofiuorobenzene, 3,4-dichloronitrobenzene, Z-chloro-S-nitrotoluene,2-chloro-S-nitroethylbenzene, 2-nitro-5-bromotoluene,2-chloro-5-nitroanisole and the like.

Compounds of Formula III utilizable in both reactions 1 and 1a includephenylenediamines, biphenyldiamines, naphthalenediamines andbi(naphthylarnines). Illustrative phenylenediamines includep-phenylenediamine, o-phenylenediamine, m-phenylenediamine,p-toluylenediamine, 2,5- dimethoxy-p-phenylenediamine,2,6-dimethyl-p-phenylenediamine, etc. Illustrative biphenyldiaminesinclude benzidine, 2,2-biphenyldiamine, 3,3'-biphenyldiamine,2,4'-biphenylidamine, 6,6-dimethyl-2,2'-biphenyldiamine, otolidine,o-dianisidine, m-tolidine, etc. Illustrative naphthalenediamines include1,4-naphthalenediamine, 1,5-naphthalenediamine, 2,6-naphthalenediamine,2-ethoxy-1,4- naphthalenediamine, Z-ethyl-1,4-naphthalenediamine, 4,8-dimethoxy-Z,G-naphthalenediamine, etc. Illustrative bi (naphthylamines)include naphthidine, 4,4-bi(2-naphthylamine 1, l -diethoxy-4,4'-biZ-naphthylamine 2,2- bi(1-naphthylamine), 2,4-bi(l-naphthylamine),2,2'-di amino-4,4'-bi-l-naphthol, etc.

Reduction of the nitrocompound (Reaction 2) is effected conveniently bycatalytic hydrogenation in a suitable solvent, again preferablydimethylformamide. Standard catalysts for the hydrogenation of aromaticnitro compounds may be used. These include palladium on charcoal andRaney nickel,

The amino compound from Reaction 2 is then reacted in a suitablesolvent, such as aqueous acetone, with the reactant RZ according toReaction 3. RZ may be an alkyl halide, such as methyl chloride, ethyliodide, propyl bromide, butyl iodide, hexyl bromide, octyl bromide,dodecyl bromide or a carboxy-substituted alkyl halide, such aschloroacetic acid; or an alkyl sulfate, such as methyl sulfate, ethylsulfate and the like; or an alkyl arylsulfonate, such as methylp-toluenesulfonate. An allyl halide, such as allyl bromide, also may beused. Other alkylating agents which may be used include acrylonitrileand alkylene oxides, such as ethylene oxide. An alkali or alkaline saltsuch as sodium carbonate or potassium carbonate also normally is used.Reaction proportions and conditions are so selected that either one ortwo R groups per amino group are introduced.

As has been indicated previously, the aryl rings of Formula I may bearinert substituents, such as lower alkyl or alkoxy. These substitutedproducts may be derived from the corresponding substituted startingmaterials of halobenzenes or naphthalenes or the nitrosubstitutedhalobenzenes or naphthalenes in Reactions 1 and 1a. As also indicatedpreviously, certain of the intermediate compounds, viz., those of thetype formed in Reactions 1 and 3 are believed to be new compounds.

Conversion of the compounds of Reactions 1 or 3 to the salts of FormulaI is effected by oxidation of the amino compounds. This reaction iscarried out in organic solvent solution by reacting the (polyamino)compound of Formula II with a silver salt of a suitable acid. Thisgeneral method is shown in Neunhoeffer et al., Ber. 92, 245 (1959).Dimethylformamide is a good solvent for use as the reaction medium,Others, such as acetone may be used. A wide variety of silver salts maybe used. These include the perchlorate (ClO fluoborate (BF tri- 4chloracetate (CCl COO-), trifiuoroacetate (CF COO*), picrate,hexafiuoroarsenate (AsF hexafluoroantimonate (SbF benzenesulfonate (C HSO' ethanesul fonate (C H SO phosphate (PO sulfate (SO; nitrate (NOchloride (Cl) and the like.

As an alternative method, particularly where R, R R and R of Formula Iare hydrogens, the oxidation of the compound of Formula II is carriedout electrolytically using a suitable electrolyte to provide the desiredanion and sufficient electric potential on the anode. The alkali metalsalts corresponding to the above silver salts may be used in a suitablesolvent such as acetone as the electrolyte.

Various aminium compounds such as tris(p-dialkylaminophenyl)aminiumsalts previously have been proposed for use in various substrates todecrease transmission in the infrared region of the spectrum. Such saltsdo absorb strongly in the near infrared region of the spectrum. However,most effective protection occurs in the vicinity of 960 millimicrons.Suitable compounds capable of broad absorption at longer wavelengths inthe near infrared have been desired but in the past have not beenavailable. It is, therefore, a principal object of the present inventionto provide compounds having such broader absorption bands.

In accordance with the present invention this object is accomplished byuse of compounds of Formula I. Compounds of this invention absorbbroadly in the near infrared region of the spectrum at wavelengthslonger than those obtained with compounds previously available. Improvedabsorption is obtained in the region of longer wave lengths betweenabout 1000 and about 1800 millimicrons. Many of the compounds also havedesirable absorption at shorter wavelengths in the near infrared region.These compounds also transmit a useful amount of visible light.

Radiant energy from the sun is frequently grouped into three regions,the near-ultraviolet, the visible and the nearinfrared. Together thesethree regions cover the range of wavelengths of from 0.290 micron toabout 5.0 microns. Somewhat arbitrarily, the near-ultraviolet spectrummay be considered to cover the region of 0.300-O.400 micron; the visiblespectrum, the region of 0.400-0.700 micron; and the near-infraredspectrum the region of .7005.0 microns.

TABLE I.APIROXIMATE DISTRIBUTION OF RADIANT ENERGY FROM SEVERAL ENERGYSOURCES Percent of total radiant energy omitte Above Sunlight (reachingearth) 5 42 54 53 Tungsten lamp, 500 \v. 0.1 10 53 Fluorescent lamp 5 3528 60 Carbon filament heater 0 1 28 99 Nonluminous heaters 0 0 1.3 100Accordingly, it may be seen that a large proportion of the energytransmitted by our common light sources serves no useful purpose withrespect to illumination, but contributes to the development of heat inthe material receiving the radiation.

TABLE II.-APPROXIMATE DISTRIBUTION OF RADIANT ENERGY OF SUNLIGHT Percentof total Percent of infrared Region This table indicates that Within thenear-infrared region, the greater part of the infrared energy isradiated within the region from about 0.7 to about 2.0 microns. Forexample, in normal sunlight some two-thirds of the radiant energy is atwavelengths of from about 0.7 to about 1.3 microns.

It also may be noted in Table II that some 4344% of the total infraredradiation in sunlight is in the region just above about 0.7 micron. Thelatter is about the upper limit of the visible range which, as notedabove, usually is defined as from about 0.4 to about 0.7 micron, hencethe near infrared designation. While by the foregoing definition thenear-infrared region extends only down to about 0.7 micron, for purposesof this invention the region of particular interest extends from about0.65 micron to about 1.3 microns. In the following discussion thisregion will be designated as the (NIR) In many circumstances it isdesirable to filter out nonvisi'ble radiations of the near-infraredregion Without materially diminishing transmission of visibleradiations. There are many potential applications for materials thatwill transmit a major portion of the visible radiations but at the sametime be at least semi-opaque to heat-producing infrared radiation,particularly that in the above-noted (NIR). Among such possibleapplications may be mentioned sunglasses, welders goggles and other eyeprotective filters, Windows, television filters, projection lenses andthe like. In many, if not most, of such uses the primary object is toprotect the human eye from the adverse elfects of radiation in the nearinfrared.

Experience has shown that sunglasses, as an illustrative example, shouldbe capable of transmitting at least about of incident visible lightshorter than about 0.65 micron. However, to provide adequate protectionfor the human eye, transmission should be less than forty percent atfrom about 0.65 to about 0.75 micron and not over about ten percentbetween about 0.75 and about 0.95 micron. Preferably, some 20% or moreof visible light will be transmitted. In the two other noted ranges,preferably transmission should not exceed about five percent and onepercent respectively.

Other protective optical filters may vary as to requirements in thevisible range. In most cases, however, transmission in the near-infraredshould not exceed the indicated limitations. This applies, for example,not only to other eye protective devices as widely different as weldersgoggles and window glass, but also to protecting inanimate material asin the case of projection lenses. Optimum protective utility, therefore,ordinarily requires relatively good transmission of radiation belowabout 0.65 micron but reduced or minimized transmission above thatvalue. Obviously complete cutoff at exactly this, or any otherWavelength, is impossible. Nevertheless, for the purposes of thisinvention, cutoff should be as sharp as possible within a minimum spreadof wavelength at about 0.65 micron.

Various organic plastic substrates are available having generallysuitable transmission properties in the visible region. Illustrativeexamples include:

cellulose derivatives such as cellulose nitrate, cellulose acetate andthe like; regenerated cellulose and cellulose ethers as for eX ample,ethyl and methyl cellulose;

polystyrene plastics such as polystyrene per se and polymers andcopolymers of various ring-substituted styrenes such for example as o-,mand p-methylstyrene and other ring-substituted styrenes as well asside-chain substituted styrenes such as alpha-, methyland ethylstyreneand various other polymerizable and copolymerizable vinylidenes;

various vinyl polymers and copolymers such as polyvinyl butyral andother acetals, polyvinyl chloride,

polyvinyl acetate and its hydrolysis products, polyvinylchloride-acetate copolymers and the like;

various acrylic resins such as polymers and copolymers of methylacrylate, methyl methacrylate, acrylamide, methylolacrylamide,acrylonitrile and the like;

polyolefins such as polyethylene, polypropylene and the like; polyestersand unsaturated-modified polyester resins such as those made bycondensation of polycarboxylic acids with polyhydric phenols or modifiedusing unsaturated carboxylic acid and further modified by reacting thealkyd with another monomer; polymers of allyl diglycol carbonate; andvarious copolymers using as a cross-linking monomer an allyl ester ofvarious acids. Of particular interest and preferred herein as substratesare cellulose acetate, methyl methacrylate, polystyrenes and polymers ofallyl diglycol carbonates.

Any one such substrate may, and usually does, vary from the others veryappreciably in its transmission of radiant energy at variouswavelengths. Nevertheless, if not modified, none meet the foregoingtransmission requirements. Some additive is necessary to decrease theinfrared transmission without adversely affecting transmission in thevisible range.

Heat resistance of the salts of this invention can be demonstrated whenthe diimonium salts are dispersed in plastic materials, or when they aredissolved in suitable solvents. They are adequately resistant toexposure to temperatures up to about 200 C. This temperature isfrequently encountered in the processing of plastic substrates such asthose discussed above. Accordingly, compounds of this invention aresuitable for purposes of use in such cases.

Products of this invention have good light and heat stability whenincorporated into organic plastic substrates. Satisfactory absorption bytransparent plastics of radiant energy in the 1000 to 2000 millimicronregion (as given off by the sun or by other light sources) has not beenpossible heretofore. This portion of infrared radiation is a sizableportion of the total infrared radiation from sunlight, incandescent andother lamps.

In use, the salts of the present invention may be incorporated in anysuitable plastic or applied on suitable transparent substrates ofplastic or glass. This is done by any of several known procedures,including for example; solution casting or dipping; hot milling;burnishin-g; or by dyeing. Organic plastic material containing the saltscan be molded into formed articles such as sheets and plates.

In any method of use, the salts may be incorporated as a barrier layerin or near one surface of a substrate or be disseminated therethrough.Choice of either practice depends on the type of protection used and thephysical method used to combine the substrate and the salt or salts.

Either practice can be used to protect the treated material. Either canalso be used to form a protective barrier between an object to beprotected and the source of the infrared radiation. In the latter case,protection is usually provided by combining salt and organic substratein a relatively thin layer or sheet which is then used as the protectivebarrier. Protection of an object also can be ob- 7 tained by coating thesalts, in a suitable vehicle, directly onto substrates such as glass orformed plastic objects whether to protect the substrate or in forming aprotective barrier for other objects.

It is not readily possible to assign limits to the amount which it isdesirable to use. In general, the limiting maximum is only an economicone. As to the minimum, it depends on whether the salt is disseminateduniformly through the substrate or is concentrated in a barrier layer ofthe same or a different substrate. When disseminated through asubstrate, usually to protect the latter, there should be provided atleast about 0.005 weight percent of the substrate. When concentrated ina barrier layer this is equivalent to about 0.01 gram per square foot ofsurface of a plastic substrate of inch thickness.

The compounds of this invention have many uses arising from the valuablecombination of infrared absorbency and transparency to visible light.These uses may be considered as falling within three major areasaccording to the function of the infrared absorber.

In the first area of use, these compounds function to filter or screenout infrared radiation and prevent its transmission through a substrateon or in which these compounds are dispersed. In this area, specificapplications are in sunglasses, welders goggles or shields, astronautsface-plates, and face-plates in fire-fighters reflective protectivesuits where transparency for vision coupled with protection of eyes frominfrared radiation are desired. Also, these compounds may beincorporated in transparent plastic sheets or films for windows, doors,skylights, etc., in building, greenhouses, automobiles, aircraft, ships,etc., to screen out infrared radiation and minimize heat build-up in theinteriors of such structures while still transmitting visible radiation.In such applications, these compounds may be dispersed in or on a rigidplastic substrate or may be dispersed in a thin plastic film useablealone or adhered to an untreated substrate, which may be glass orplastic. For example, for automobile safety glass Windshields, theplastic interlayer between the two sheets of glass may have the infraredabsorber incorporated therein. Also, for store, oflice, or residentialwindows, a plastic film containing these compounds may be adhered to theglass or may be hung as a window shade immediately inside the window androlled up when not needed. For sunglasses, aircraft windows, andsky-lights, these compounds may be incorporated in the plastic of whichsuch articles are made, either as a uniform dispersion throughout or asa barrier layer adjacent one surface thereof.

In the second area of use, these compounds function to absorb infraredradiation and accumulate it as heat in order to increase the temperatureof those materials containing these compounds. Thus, these compounds canbe incorporated onto natural or synthetic fibers used in clothing tomake such clothing warmer in cold climates even though such clothing maybe light in color. Also, these compounds can be dissolved in water orincorporated in plastic particles, flakes, or film strips which fioat onwater to increase the rate of evaporation of the water (or other liquid)by solar or other infrared radiation for production of distilled wateror for increasing salt concentration in the remaining liquor or forrecovery of salt from solution. Further, these compounds can beincorporated into materials to improve drying rates withoutsubstantially changing the color of such materials, as, for example,colored inks, paints, enamels, bathing suits, etc. Likewise,incorporation of these compounds into polymerizable materials can serveto increase the rate of polymerization under infrared radiation byincreasing the efficiency with which such radiation is absorbed. Also,since different colors absorb radiation at different rates, varyingamounts of these compounds can be added to inks, paints, or enamels ofvarious colors to so modify their drying rates as to make them uniformregardless of color 8 for ease, uniformity, and economy in processingarticles coated therewith.

Several processes currently in commercial operation use powdered inkformulations which are placed on paper or other substrate and fused inplace byinfr'ared radiation. In some reproduction and copying systems,the powdered ink formulations, which comprise carbon black (for infraredabsorption capability and optical contrast with background) andthermoplastic polymer resins, are electrostatically attracted to thedesired location either on metal and then transferred to paper ordirectly on specially coated paper. In such processes, only black inkshave been useable to date. The present compounds can provide thenecessary infrared absorption while permitting pigments of variouscolors to be used in such processes. Also, powdered inks are used toprovide a raised printing on greeting cards, match boxes, calling cards,etc., by a process which involves printing a design on paper with aclear adhesive mixture and then coating with the powdered ink whichadheres only to the adhesive-printed areas. This paper is then passedunder an infrared source to melt and thus fix the ink. Incorporation ofthese compounds into these inks can reduce the heat required in theinfrared source, increase the speed with which the inks can be fused,permit a wider range of colors to be used without danger of scorchingthe paper background before the powdered ink is set, and permit use oflight colored inks on dark colored background paper without scorchingthe dark paper.

Some photothermography systems of photoreproduction, such as theThermofax system of copying, use a paper coated to make it more heatsensitive during the development of the image by exposure to infraredradiation. Incorporation of these compounds into the surface coating ofthe paper used for this and similar processes would make the paper evenmore heat sensitive without losing contrast between the printing andbackground making feasible lower operating temperatures or fasteroperation of copying devices using such paper.

Micro-encapsulation is the process of coating materials in the form ofsmall spheres or capsules (diameters of about 1 to 200 microns) withnatural or synthetic polymeric materials, such aspolymethylmethacrylate. The coating retains the contents in finelydivided state, in each separate sphere, until such are released for useby rupturing the capsule walls, which can be by mechanical means, suchas pressure, or by application of heat, such as by exposure to radiantenergy. The incorporation of the compounds of this invention into thecoating makes the wall more sensitive to rupture by exposure to infraredradiation, thereby requiring less exposure time or lower intensityinfrared radiation to effect rupture. Also, by use of different amountsof these compounds in the coatings of different capsules, such capsulescan be made to rupture on absorption of different amounts of radiation,thereby producing a record of the relative quantities of infraredradiation impinging on any areas containing mixtures of such capsules.

Additionally, these compounds can serve to magnify the effects ofinfrared radiation falling on sensing elements when such elements arecoated with such compounds simplifying amplification circuitry toconvert signals from such elements to useable currents or voltages.Thus, sensors for fire detection devices may be so treated to make themmore sensitive to the presence of flames. Also, sensors in dataprocessing machines may be so treated to make them more sensitive toheat effects where such are used to operate electrical circuits.

In the third area of use, these compounds function by a miscellaneousassortment of mechanisms. Included 1n this category are suchapplications as incorporating these compounds into colored inks for usein ball-point or other pens so such inks will reproduce by thoseprocesses,- such as Thermofax, which rely on infrared absorption by theink on the document being copied. At present, carbon black must be used,limiting the inks for such pur- 9 pose to black inks. Also incorporationof such compounds EXAMPLE 2 into face creams and dyes for clothing andother fabrics can serve to render the wearer invisible to infrareddeteci51 :32 2igiifgfigggfggigg fig tion devices, such as theSniperscope or Snooperscope q which operate by reflection of infraredradiation from the 5 The Procedure f Example 1 1s followed substitutinobject, e.g., soldiers, tents, netting over guns, etc., to be anequivalent amount of silver hexafluoroarsenate for the detected back toa detector. Further, incorporation of Silver hFifafluofoafltlmonate- TheProduct melts Wlth such compounds into the paints used to covernon-luminous composition by 170 C.

radiating surfaces, such as steam or hot water radiators, radiantheating wall, floor, or ceiling panels, etc. can serve EXAMPLE 3 toincrease the efliciency of radiation of heat energy from A series of pbenzoquinonediimoniurn salts of the such bodies to the enclosuresurrounding them even though above formula are prepared by the generalprocedure of the paints are light in color or contain metal pigments.Example 1 using the appropriate N,N,N,N-tetrakis(p- Since growth rate ofplants is sensitive to the wave dialkylaminophenyl)-p-phenylenediamineand silver salt. lengths of incident light, interposition of a film orsheet The substituents are summarized in the following listing:containing these compounds between such plants and the Compound: Alkyl Xradiant energy source can serve to modify this rate. For (a) CH3 ASFGexample, germination of lettuce seeds, and the like, is pro (b) C1331]:gr pe moted most at about 650 millimicrons and 1s 1nh1b1ted d Z fi mostat about 730 millimicrons. By suitable selection of these compounds andconcentration in such film or sheet, substantially all the radiation at730 millimicrons can be absorbed while a high proportion of that at 650milli- EXAMPLE4 microns can be transmitted to these plants to maximizeN,N,N',N'-tetrakis(p-diethylaminophenyl)diphenothe rate of germination.quinonebis(imonium hexafiuoroarsenate) The foregoing merely indicatessome of the numerous To a solution of 0.77 part (0.001 mol) of N,N,N,N'-uses for these compounds. From this listing and thepropertetrakis(p-diethylaminophenyl) benzidine in 40 parts of ties ofthese compounds discussed elsewhere herein, many acetone is addeddropwise with stirring a solution of 0.60 other uses for these compoundswill immediately become 40 part (0.002 mole) of silverhexafluoroarsenate in 5 parts apparent. of acetone. After stirring forabout 30 minutes the mix- The invention will be further illustrated inconjunction ture is filtered and the filtrate diluted with 200 parts ofwith the following examples. Therein, unless otherwise ethyl ether. Oncooling in Dry-Ice-acetone, the product noted, all parts and percentagesare by weight and all separates. temperatures are in degrees centigrade.EXAMPLE 5 T'wo compounds of the above formula are prepared by theprocedure of Example 4 substituting an equivalent EXAMPLE 1N,N,N,N-tetrakis (p-diethylaminophenyl) -p-benzoquinone-bis(imoniumhexafluoroantimonate) To mixture of 1 Parts (0.002 mol) of N N amount ofthe appropriate silver salt for the silver hexa-N'-N'-tetrakis(p-diethylaminophenyl) p phenylenedifiuoroarsenate asShown below amine in 20 parts of acetone is added 1.38parts (0.004Compound: X mol) of silver hexafluoroantimonate. After stirring for one(a) C10 half hour, the dark blue solution is filtered and the filtrate(b) SbF diluted with 100 parts of ether. The mixture is cooled andEXAMPLE 6 the solid which separates is collected, washed with ether Aseries of diimonium compounds of the above formuand petroleum ether anddried. There is obtained 2.1 parts la are prepared by the generalprocedure of Example 1, of product melting with decomposition by 216 C.7 using the appropriate N,N,N',N'-tetrakis(p-substitutedaminophenyl)-p-phenylenediamine and silver hexafluoroantimonate.

(:1) CaH5CH2 CQH5CH2- (b) l-naphthylmcthyl l-naphthylmetliyl (c) CFaC H((1) IJ-FCBIILCIIP p-FCoH-1CH2- (e) CaHs II EXAMPLE7 N,N,N',N tetrakis(4[di(2 hydroxyethyl)amino] phen-yl) p benzoquinonebis(imoniurnhexafluoroantimonate) To a solution of 3.3 parts (0.004 mole) ofN,N,N',N'-

(a is an expression of the degree of absorption. It

M-[ -hydr0xyethyl)amino]phenyl) p phen- 20 is calculated using thefollowing relationship:

ylenediamine in 30 parts of methanol is added 2.74 parts (0.008 mole) ofsilver hexafiuoroantimonate. After stirring for one hour, the mixture isfiltered and the residue is Washed with methanol. The combined filtratesare diluted with ether and cooled in a Dry-Ice-acetone bath. 25

The product which separates is collected by filtration, washed withpetroleum ether and dried.

EXAMPLE 8 N,N,N,N'-tetrakis( 4- [di Z-hydroxyethyl) amino] phenyl -p -'benzoquinonebis (imonium nitrate) i To The procedure of Example 7 isfollowed substituting 1.36 parts (0.008 mole) of silver nitrate for thesilver hexafiuoroantimonate.

EXAMPLE 9 N,N,N',N'-tetraphenyl-p-benzoquinonebis-(imoniumhexafluoroantimonate) An electric current is passed through a cellcontaining an anolyte consisting of 1.03 g. (0.0025 mole) of N,N,-N',N-tetraphenyl-pphenylenediamine, 2.59 g. (0.010 mole) of sodiumhexafiuoroantimonate and 100 ml. of acetone, and a catholyte consistingof 18.1 g. of sodium hexafluoroantimonate and 700 ml. of acetone. Thecell consists of a rotating platinum anode placed in a porous Alundumcup containing the anolyte and immersed in a glass vessel containing thecatholyte and a carbon cathode. During a 4.5 hour period the anodepotential is maintained at +1.3 volts with respect to a silver chloridereference electrode containing 0.1 N hydrochloric acid electrolyte. Theproduct is isolated from the anolyte by conventional procedures.

Similarly effective infrared absorbing compounds may be prepared afterthe fashion of Example 9 by utilizing as a starting reactant, in placeof the N,N,N',N'-tetraphenyl p phenylenediamine, substituted N,N,N,N'-tetraryl arylene diamines where the substituents are present on the arylnuclei. Thus, substituents, such as alkyl (methyl, ethyl, propyl, butyl,etc.), alkoxy (methoxy, ethoxy, butoxy, etc.), aryl (phenyl), alkaryl(tolyl), and acyl (acetyl, etc.) may suitably be present without ad-EXAMPLE 10 In accordance with the foregoing discussion, spectralabsorption curves of solutions of the products of Examples 1, 2, 3e, 6and 9 in acetone were determined in the near infrared region of thespectrum. Illustrative results are shown below.

Absorption max.

Example No. (Mp) EXAMPLE 11 The product of Example 2 is incorporatedinto a cellulose acetate film by casting an acetone solution of theplastic and the additive on plate glass. The thin film exhibits strongnear-infrared absorption having a peak at 1075 111,44. The lightstability of the additive during exposure in an Atlas Fade-Orneter ismeasured spectrally. Curves are taken before and after each period ofexposure. The percent of additive remaining is calculated from theformula percent remaining-A X 100 where A is the absorbence at 950millimicrons before exposure and A is the absorbence at 950 millimicronsafter T hours of exposure. Illustrative results are shown below.

wherein A represents a benzoquinonoid or naphthaquinonoid radical, andwherein B, D, E and F represent benzene or naphthalene radicals; n is 1or 2; R, R R and R represent hydrogen, alkyl, alkoxy, alkenyl, benzyl,phenyl, tolyl, acetyl, benzoyl or radicals, said R and R in turnrepresenting hydrogen, alkyl, alkenyl, benzyl, naphthylmethyl ortrifluoroacetyl radicals; said A, B, D, E and F and R through R whichare other than hydrogen being unsubstituted or substituted as follows:said A being substituted by lower alkyl, lower alkoxy or hydroxy; saidB, C, D and F being substituted by lower alkyl, lower alkoxy or halogen;and said R and R where they are alkyl, being substituted by hydroxy orcarboxy and, where they are benzyl, being substituted by halogen; and X-represents an anion.

2. N,N,N,N' tetrakis(p-diethylaminophenyl)-p-benzoquinonebis (imoniumhexafiuoroantimonate) 3. N,N,N,N tetrakis(p-diethylaminophenyl)-p-benzoquinonebisfimonium hexafluoroarsenate) 4.N,N,N,N tetrakis (p-dimethylaminophenyl)-p-benzoquinonebis (imoniumhexafluoroantimonate) 5. N,N,N',N tetrakis(p-dimethylaminophenyl)-p-benzoquinonebis(imonium hexafluoroarsenate) 6.N,N,N',N' tetrakis(p-dipropylaminophenyl)-p-benzoquinonebis(imoniumhexafluoroantimonate) 7. N,N,N',N tetrakis(p-dipropylaminophenyl)-p-benzoquinonebis imonium tetrafluoroborate) 8. N,N,N',N' tetrakis(p-dibutylaminophenyl)-p-benzoquinonebis(imonium hexafluoroantimonate)9. N,N,N,N' tetrakis(p-dioctylaminophenyl)-p-benzoquin0nebis(imoniumhexafluoroantimonate) 10. N,N,N',N'tetrakis(p-didodecylaminophenyl)-pbenzoquinonebis(im0niumhexafluoroarsenate) References Cited UNITED STATES PATENTS 3,115,50612/1963 Acker et a1. 260396 LORRAINE A. WEINBERGER, Primary Examiner L.A. THAXTON, Assistant Examiner U.S. C1.X.R. 252300

